An eerie tale of aliens among us, this is, sadly, not science-fiction but cold, pulse-stopping fact. When 21 Chinese "cockle pickers" drowned in Morecambe Bay in 2004, the episode exposed a secret immigrant underworld that most of us would rather not acknowledge. In Ghosts, the invisible masses finally get a voice. And that voice doesn't say, "Give me a job"; it says, "Get me the hell out of here." Welcome to . And have a nice slave.
Armed with two years' research and the articles of undercover journalist Hsiao-Hung Pai, Ghosts holds enough combustible matter on illegal immigration to seriously knock a nation's pride. Given his tenacious reputation for getting in the picture, the presence of cult docu-star Nick Broomfield suggests an invasive, get-mucky approach to the material – some reportage, some argy bargy, the whole scandal exploded in droll, lazy voiceover. Well, maybe even Broomfield sensed the walking-film-unit thing was getting a little tattered around the headphones – a dramatic script and a step behind the camera has settled his gonzo vision and sent his art forward.
Narratively speaking, the story of Ai Qin's passage from rural to sweatshop is pretty traditional and, for anybody who caught Maria Full Of Grace, certainly recognisable. What makes Ghosts a standout is its relentless bid for authenticity. Not only are the same locations and locals deployed, but the entire Chinese cast is made up of former illegal immigrants. Performance or re-enactment? Whatever the technique, it isn't a gimmick – the results are all to see in Ai Qin's mesmerising lead, a performance without edges, safety nets or pretence. It's impossible not to empathise with the cruel Catch-22 in which she finds herself.
If all this sounds heavy, worthy or gruelling, well, you could say the same for United 93. That gripped. This does too, although the pull's more hypnotic, the handheld visuals more haunting, the borders between docu and drama blurred even further. There is hope in this movie, and a suprising streak of humour too. Overwhelmingly, though, this is simmering, impassioned cinema, the kind this country now seems almost too scared to produce - a homegrown film about homefront issues with a story worth sharing anywhere. You don't get many of those to the pound in a cinematic year.